Cochlear implant systems including magnetic flux redirection means

ABSTRACT

An exemplary cochlear implant system includes a component that houses a circuit board comprising electronic circuitry that generates one or more signals, an induction coil that transmits the one or more signals by generating a telemetry magnetic field, and a telemetry flux guide positioned between and in direct contact with a top surface of the induction coil and a bottom surface of the circuit board.

RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 13/128,755, filed May 11, 2011, which applicationis a U.S. National Stage Entry of PCT Application No. PCT/US09/64033,filed Nov. 11, 2009, which application claims priority to U.S.Provisional Patent Application No. 61/113,675, filed Nov. 12, 2008, U.S.Provisional Patent Application No. 61/113,708, filed Nov. 12, 2008, andU.S. Provisional Patent Application No. 61/139,567, filed Dec. 20, 2008.The contents of all of these applications are incorporated herein byreference in their respective entireties.

BACKGROUND INFORMATION

The sense of hearing in human beings involves the use of hair cells inthe cochlea that convert or transduce audio signals into auditory nerveimpulses. Hearing loss, which may be due to many different causes, isgenerally of two types: conductive and sensorineural. Conductive hearingloss occurs when the normal mechanical pathways for sound to reach thehair cells in the cochlea are impeded. These sound pathways may beimpeded, for example, by damage to the auditory ossicles. Conductivehearing loss may often be helped by the use of conventional hearing aidsthat amplify sound so that audio signals reach the cochlea and the haircells. Some types of conductive hearing loss may also be treated bysurgical procedures.

Sensorineural hearing loss, on the other hand, is due to the absence orthe destruction of the hair cells in the cochlea which are needed totransduce audio signals into auditory nerve impulses. Thus, many peoplewho suffer from severe to profound sensorineural hearing loss are unableto derive any benefit from conventional hearing aid systems. To overcomesensorineural hearing loss, numerous cochlear implant systems, orcochlear prosthesis, have been developed. Cochlear implant systemsbypass the hair cells in the cochlea by presenting electricalstimulation directly to the auditory nerve fibers. Direct stimulation ofthe auditory nerve fibers leads to the perception of sound in the brainand at least partial restoration of hearing function.

Cochlear implant systems typically include a cochlear stimulator that isimplanted beneath the scalp of a patient. An external control assemblylocated external to the patient's scalp may be used by the patient tocontrol and adjust various operational parameters of the implantedcochlear stimulator. An inductive link is commonly used to transmittelemetry signals from the external control assembly to the implantedcochlear stimulator. To this end, the external control assembly oftenincludes an inductive coil that produces a telemetry signal bygenerating an electro-magnetic field that is picked up by a receiver onthe implanted cochlear stimulator. The inductive coil may be housed inan external headpiece that is positioned on a patient's head to transmitthe telemetry signal through the patient's scalp to the implantedreceiver. The external control often includes a retention magnet forsecuring the headpiece to the patient's head so that the induction coilis properly positioned adjacent to the implanted receiver.

In a conventional cochlear implant system, electronic circuitry includedwithin the external control assembly is not placed in relative closeproximity to the induction coil and the retention magnet due to lossesand interference caused by magnetic flux associated with the inductioncoil and the retention magnet. Hence, the electronic circuitry istypically housed within a behind-the-ear unit, for example, while theinduction coil and the retention magnet are housed separately within aheadpiece. Such a configuration is undesirable for many cochlear implantpatients.

SUMMARY

Exemplary cochlear implant systems include a circuit board havingelectronic circuitry configured to generate one or more signalsconfigured to direct electrical stimulation of one or more stimulationsites within a patient, an induction coil configured to transmit atelemetry signal by generating a telemetry magnetic field, and atelemetry flux guide positioned between the induction coil and thecircuit board. The telemetry flux guide is configured to direct magneticflux of the telemetry magnetic field away from the circuit board.

Exemplary cochlear implant systems include a circuit board havingelectronic circuitry configured to generate one or more signalsconfigured to direct electrical stimulation of one or more stimulationsites within a patient, a retention magnet configured to produce aretention magnetic field for securing one or more components of thecochlear implant system to a head of said patient, and a retention fluxguide positioned between the retention magnet and the circuit board. Theretention flux guide is configured to direct magnetic flux of theretention magnetic field away from the circuit board.

Exemplary external headpieces for use in cochlear implant systemsinclude a circuit board having electronic circuitry configured togenerate one or more signals configured to direct electrical stimulationof one or more stimulation sites within a patient. The externalheadpieces further include an induction coil configured to transmit atelemetry signal by generating a telemetry magnetic field and atelemetry flux guide positioned between the induction coil and thecircuit board. The telemetry flux guide is configured to direct magneticflux of the telemetry magnetic field away from the circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments of theprinciples described herein and are a part of the specification. Theillustrated embodiments are merely examples and do not limit the scopeof the disclosure.

FIG. 1A illustrates an exemplary cochlear implant system according toprinciples described herein.

FIG. 1B illustrates a portion of an exemplary cochlear implant systemaccording to principles described herein.

FIG. 2 is a functional block diagram of an exemplary sound processor andimplantable cochlear stimulator according to principles describedherein.

FIG. 3 illustrates a schematic structure of the human cochleahighlighting elements according to principles described herein.

FIG. 4 illustrates an exemplary configuration of a cochlear implantsystem according to principles described herein.

FIG. 5A is an exploded perspective view of an exemplary externalheadpiece according to principles described herein.

FIG. 5B is a perspective view of a portion of an exemplary externalheadpiece according to principles described herein.

FIG. 5C is a cross-sectional side view of a portion of an exemplaryexternal headpiece according to principles described herein.

FIG. 6 illustrates magnetic flux surrounding an induction coil and aretention magnet in an exemplary external headpiece according toprinciples described herein.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements.

DETAILED DESCRIPTION

Cochlear implant systems including an external headpiece that houses acircuit board having electronic circuitry configured to generate one ormore signals configured to control an operation of an implantablecochlear stimulator are described herein. The external headpiece furtherincludes an induction coil configured to transmit a telemetry signal tothe implantable cochlear stimulator by generating a telemetry magneticfield. The external headpiece may additionally include a telemetry fluxguide positioned between the induction coil and the circuit board. Thetelemetry flux guide may be configured to direct magnetic flux of thetelemetry magnetic field away from the circuit board.

In some examples, the external headpiece further includes a retentionmagnet configured to produce a retention magnetic field for securing theheadpiece to a head of the patient. In this case, the external headpiecemay also include a retention flux guide positioned between the retentionmagnet and the circuit board. The retention flux guide may be configuredto direct magnetic flux of the retention magnetic field away from thecircuit board.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present systems and methods. It will be apparent,however, to one skilled in the art that the present systems and methodsmay be practiced without these specific details. Reference in thespecification to “one example” or “an example” means that a particularfeature, structure, or characteristic described in connection with theexample is included in at least one example. The appearance of thephrase “in one example” in various places in the specification are notnecessarily all referring to the same example.

FIG. 1A illustrates an exemplary cochlear implant system 100. Thecochlear implant system 100 of FIG. 1A includes a sound processorportion 102 and a cochlear stimulation portion 104. The sound processorportion 102 may include a sound processor 106, a microphone 108, and/oradditional circuitry as best serves a particular application. Thecochlear stimulation portion 104 may include an implantable cochlearstimulator 110, a number of electrodes 112 disposed on an electrode lead114, and/or additional circuitry as best serves a particularapplication. The components within the sound processor portion 102 andthe cochlear stimulation portion 104 will be described in more detailbelow.

The microphone 108 of FIG. 1A is configured to sense audio signals andconvert the sensed signals to corresponding electrical signals. In someexamples, the audio signal may include speech. The audio signal mayadditionally or alternatively include music, noise, and/or other sounds.The electrical signals are sent from the microphone 108 to the soundprocessor 106 via a communication link 116. Alternatively, themicrophone 108 may be connected directly to, or integrated with, thesound processor 106. The sound processor 106 processes these convertedaudio signals in accordance with a selected sound processing strategy togenerate appropriate stimulation parameters for controlling theimplantable cochlear stimulator 110. These stimulation parameters mayspecify or define the polarity, magnitude, location (i.e., whichelectrode pair or electrode group receive the electrical stimulation),stimulation rate, timing (i.e., when the electrical stimulation is to beapplied to a particular electrode pair), spectral tilt, and/or any othercharacteristic of the electrical stimulation that is generated by theimplantable cochlear stimulator 110.

The electrode lead 114 shown in FIG. 1A is configured to be insertedwithin a duct of a cochlea. As shown in FIG. 1A, the electrode lead 114includes a multiplicity of electrodes 112, e.g., sixteen electrodes,spaced along its length. It will be understood, however, that any numberof electrodes 112 may be disposed on the electrode lead 114. Theelectrode lead 114 may be substantially as shown and described in U.S.Pat. No. 4,819,647 or 6,218,753, each of which is incorporated herein byreference in its respective entirety. As will be described in moredetail below, electronic circuitry within the implantable cochlearstimulator 110 is configured to generate and apply electricalstimulation to one or more stimulation sites within the cochlea viaselected stimulation channels (i.e., pairs or groups of the individualelectrodes 112) in accordance with a specified stimulation strategydefined by the sound processor 106.

In some examples, the sound processor 106 and the microphone 108comprise an external portion of the cochlear implant system 100, and theimplantable cochlear stimulator 110 and the electrode lead 114 comprisean implantable portion of the system 100 that is implanted within apatient's body. In alternative embodiments, one or more portions of thesound processor 106 are included within the implantable portion of thecochlear implant system 100.

The implantable cochlear stimulator 110 and the sound processor 106 maybe communicatively coupled via a suitable data or communication link118, such as a telemetry communication link, as will be described inmore detail below. It will be understood that the data communicationlink 118 may include a bi-directional communication link and/or one ormore dedicated uni-directional communication links. In some examples,the external and implantable portions of the cochlear implant system 100may each include one or more inductive coils configured to transmit andreceive power and/or control signals via the communication link 118. Thecontrol signals may include, for example, the magnitude and polarity ofelectrical stimulation representing a sensed audio signal. The externalcoil may also transmit power from the external portion to theimplantable portion of the cochlear implant system 100. Powertransmitted to the implantable portion may be used to operate theimplantable portion.

FIG. 1B illustrates a portion of an exemplary cochlear implant systemshowing a communication link 118 comprising a telemetry communicationlink that may be used in accordance with the present systems andmethods. As illustrated in FIG. 1B, an external portion of the cochlearimplant system 100 may include an external induction coil 120 and animplantable portion of the cochlear implant system 100 may include animplantable induction coil 122. The external induction coil 120 may becommunicatively coupled to the sound processor 106 and the implantableinduction coil 122 may be communicatively coupled to the implantablecochlear stimulator 110.

The external induction coil 120 and the implantable induction coil 122may include any suitable type of coil capable of generating and/orreceiving an electro-magnetic field. For example, the external inductioncoil 120 and the implantable induction coil 122 may each include ametallic wire or tube wound in a coiled or otherwise loopedconfiguration. An alternating current may be directed from the soundprocessor 106 through the external induction coil 120, therebygenerating a magnetic field surrounding the external induction coil 120.The external induction coil 120 may be positioned near the implantableinduction coil 122 such that the implantable induction coil 122 ispositioned at least partially within the magnetic field generated by theexternal induction coil 120. The magnetic field generated by theexternal induction coil 120 may cause an electric current to begenerated in the internal induction coil 120. The electric currentgenerated in the internal induction coil 120 may be directed from theinternal induction coil 120 to the implantable cochlear stimulator 110.Accordingly, an electric current generated by the sound processor 106may be transferred to the implantable cochlear stimulator 110 throughthe communication link 118 comprising the external induction coil 120and the implantable induction coil 122.

The communication link 118 may function as a telemetry link between thesound processor 106 and the implantable cochlear stimulator 110. Forexample, the external induction coil 120 may transmit one or moretelemetry signals to the implantable induction coil 122 by generating atelemetry magnetic field as electric current is passed through theexternal induction coil 120. The telemetry magnetic field generated bythe external induction coil 120 may produce an electric current in theimplantable induction coil 122, as described above. The currentgenerated in the implantable induction coil 122 by the telemetrymagnetic field generated by the external induction coil 120 may be usedto transfer signals representative of data and/or other information tothe implantable cochlear stimulator 110 and/or may be used to transferpower to the implantable cochlear stimulator 110.

In some examples, the communication link 118 may be used to transmittelemetry signals from the implantable cochlear stimulator 110 to thesound processor 106. For example, data acquired by the electrodes 112and/or status indicators generated by the cochlear stimulator 112 may betransmitted to sound processor 106 via the communication link 118. Tothis end, implantable induction coil 122 may transmit telemetry signalsto the external induction coil 120 by generating a telemetry magneticfield. The implantable cochlear stimulator 110 may cause a current toflow through the implantable induction coil 122 to generate thetelemetry magnetic field. The external induction coil 120 may bepositioned at least partially within the telemetry magnetic fieldgenerated by the implantable induction coil 122. The magnetic field maycause an electric current to be generated in the external induction coil120. The current generated in the external induction coil 120 may beused to transfer data and/or other signals to the sound processor 106.

The communication link 118 may include more than one external inductioncoil 120 and/or more than one implantable induction coil 122. Forexample, a first external induction coil and a first implantableinduction coil may be used to transfer data and/or power from the soundprocessor 106 to the implantable cochlear stimulator 110. A secondexternal induction coil and a second implantable induction coil may beused to transfer data from the implantable cochlear stimulator 110 tothe sound processor 106.

FIG. 2 is a functional block diagram of an exemplary sound processor 106and implantable cochlear stimulator 110. The functions shown in FIG. 2are merely representative of the many different functions that may beperformed by the sound processor 106 and/or the implantable cochlearstimulator 110.

As shown in FIG. 2, the microphone 108 senses an audio signal, such asspeech or music, and converts the audio signal into one or moreelectrical signals. These signals are then amplified in audio front-end(AFE) circuitry 202. The amplified audio signal is then converted to adigital signal by an analog-to-digital (A/D) converter 204. Theresulting digital signal is then subjected to automatic gain controlusing a suitable automatic gain control (AGC) function 206.

After appropriate automatic gain control, the digital signal is thenprocessed in one of a number of digital signal processing or analysischannels 208. For example, the sound processor 106 may include, but isnot limited to, sixteen analysis channels 208. Each analysis channel 208may respond to a different frequency band of the sensed audio signal dueto a series of band pass filters 210.

As shown in FIG. 2, each of the m analysis channels 208 may also includean energy detection stage (D1-Dm) 212. Each energy detection stage 212may include any combination of circuitry configured to detect the amountof energy contained within each of the m analysis channels 208. Forexample, each energy detection stage 212 may include a rectificationcircuit followed by an integrator circuit.

After energy detection, the signals within each of the m analysischannels 208 are forwarded to a mapping stage 214. The mapping stage 214is configured to map the signals in each of the m analysis channels 208to one or more of M stimulation channels 218. In other words, theinformation contained in the m analysis channels 208 is used to definethe electrical stimulation pulses that are applied to the patient by theimplantable cochlear stimulator 110 via the M stimulation channels 218.As mentioned previously, pairs or groups of individual electrodes 112may make up the M stimulation channels 218.

In some examples, the mapped signals are serialized by a multiplexer 216and transmitted to the implantable cochlear stimulator 110. Theimplantable cochlear stimulator 110 may then apply electricalstimulation via one or more of the M stimulation channels 218 to one ormore stimulation sites within the duct of the patient's cochlea. As usedherein, the term “stimulation site” will be used to refer to a targetarea or location to which the electrical stimulation is applied. Forexample, a stimulation site may refer to any location within a region ofauditory nerve tissue (e.g., auditory nerve tissue 306 shown in FIG. 3).

FIG. 3 illustrates a schematic structure of the human cochlea 300. Asshown in FIG. 3, the cochlea 300 is in the shape of a spiral beginningat a base 302 and ending at an apex 304. Within the cochlea 300 residesauditory nerve tissue 306, which is denoted by Xs in FIG. 3. Theauditory nerve tissue 306 is organized within the cochlea 300 in atonotopic manner. Low frequencies are encoded at the apex 304 of thecochlea 300 while high frequencies are encoded at the base 302. Hence,each location along the length of the cochlea 300 corresponds to adifferent perceived frequency. A cochlear prosthesis may therefore beimplanted within a patient with sensorineural hearing loss andconfigured to apply electrical stimulation to different locations withinthe cochlea 300 to provide the sensation of hearing. For example,electrode lead 114 may be disposed within the cochlea 300 such thatelectrodes 112 contact auditory nerve tissue 306 within the cochlea 300.Electrical stimulation may be applied by the electrodes 112 to theauditory nerve tissue 306.

FIG. 4 illustrates an exemplary configuration of cochlear implant system100 that may be used to apply electrical stimulation one or morestimulation sites within the cochlea 300. As shown in FIG. 4, theexternal portion of the cochlear implant system 100 may include anexternal headpiece 400 configured to be worn on an exterior of a head402 of the patient. The external headpiece 400 may include variouscomponents of the sound processor portion 102, including the externalinduction coil 122 (not shown), as will be described in greater detailbelow. The external headpiece 400 may additionally include electroniccircuitry, such as circuitry comprising at least a portion of the soundprocessor 106. The external headpiece 400 may be electrically connected,either directly or indirectly, to a microphone 108 (not shown)positioned in or near the patient's ear via a communication line 404.The headpiece 400 may additionally include a retention magnet toposition and maintain the headpiece 400 in a proper orientation on thehead 402, as will be described in greater detail below.

As shown in FIG. 4, an implantable cochlear stimulator 110 may bedisposed underneath the skin 406 of the patient. A lead 114 with aplurality of electrodes 112 disposed on a distal portion thereof may becoupled to the implantable cochlear stimulator 110 and positioned suchthat the electrodes 112 are disposed within the cochlea 300.

In some examples, the implantable cochlear stimulator 110 may include areceiver 408 configured to facilitate communication with the externalheadpiece 400. The receiver 408 may include the implantable inductioncoil 122 (not shown) described above.

The external induction coil 120 in the external headpiece 400 and theimplantable induction coil 122 in the receiver 408 may formcommunication link 118. As described above, data and/or power may betransmitted between the sound processor portion 102 and the cochlearstimulation portion 104 via the communication link 118. For example, theexternal induction coil 120 in the external headpiece 400 may transmit atelemetry signal across the skin 406 to the implantable induction coil122 in the receiver 408. Additionally or alternatively, the implantableinduction coil 122 in the receiver 408 may transmit a telemetry signalacross the skin 406 to the external induction coil 120 in the externalheadpiece 400.

FIGS. 5A-5C illustrate an exemplary external headpiece 400 that may beused in accordance with present systems and methods. The componentsshown in FIGS. 5A-5C are merely illustrative of the many differentcomponents that may be included within headpiece 400. Additional oralternative components may be included within headpiece 400 as may servea particular application.

FIG. 5A is an exploded perspective view of the exemplary externalheadpiece 400 showing various components of the external headpiece 400.FIG. 5B is a perspective view of the exemplary external headpiece 400shown without a headpiece cover. FIG. 5C is cross-sectional side view ofthe exemplary external headpiece 400 shown without a headpiece cover. Asshown in FIGS. 5A-5C, the external headpiece 400 may include a headpiececover 500 in which a headpiece cavity 502 is defined. The externalheadpiece 400 may additionally include a headpiece base 504 that may beattached to the headpiece cover 500. Components in the externalheadpiece 400 may be housed in the headpiece cavity 502 such that theyare substantially surrounded by headpiece cover 500 and the headpiecebase 504.

The external headpiece 400 may include a circuit board 506 (e.g., aprinted circuit board) having electronic circuitry 508 disposed thereon.The electronic circuitry 508 may be disposed on any suitable portions ofthe circuit board 506. A bottom surface 510 of the circuit board 506 mayface generally towards the headpiece base 504. The electronic circuitry508 may include the sound processor 106 or at least a portion of thesound processor 106. The electronic circuitry 508 may be configured todirect the implantable cochlear stimulator 110 to generate and applyelectrical stimulation to one or more stimulation sites within thecochlea 300 of a patient by transmitting control parameters (including,but not limited to, stimulation parameters) to the implantable cochlearstimulator 110 via communications link 118. The electronic circuitry 508may additionally or alternatively be configured to transmit power to theimplantable cochlear stimulator 110 and may be configured to receivedata from the cochlear stimulator 110.

The external headpiece 400 may further include an induction coil 512disposed below the bottom surface 510 of the circuit board 506. Theinduction coil 512 may include a metallic wire or tube wound in a coiledconfiguration. In some examples, the induction coil 512 may include acoiled wire arranged in a generally disc-shaped and/or annular-shapedholder. It will be recognized that the induction coil 512 may have anysuitable size and shape as may serve a particular application.

The induction coil 512 may have a top surface 514 and an interior radialsurface 516, as illustrated in FIG. 5A. The induction coil 512 may beseated in the headpiece base 504. Accordingly, the induction coil 512may be in close proximity to the head 402 of the patient when theheadpiece base 504 is adjacent to the head 402.

In some examples, the external headpiece 400 may additionally include atelemetry flux guide 518 positioned or disposed between the circuitboard 506 and the induction coil 512. The telemetry flux guide 518 mayhave a generally annular shape with an inner radial surface 520 definingan aperture extending through a central portion of the telemetry fluxguide 518. The telemetry flux guide may be adjacent to the bottomsurface 510 of the circuit board 506 and the top surface 514 of theinduction coil 512.

The telemetry flux guide 518 may include any material suitable fordirecting magnetic flux away from the circuit board 506. For example,the telemetry flux guide 518 may include a material having a relativelyhigh resistivity that provides a low reluctance path for magnetic fluxof the telemetry magnetic field. Additionally, the telemetry flux guide518 may include a powdered material, such as a powdered metallicmaterial having a relatively small particle size, in order to preventthe generation of eddy current in the telemetry flux guide 518. Forexample, eddy currents might be generated in a solid conductive material(as opposed to a powdered conductive material) in the presence of thetelemetry magnetic field since the telemetry magnetic field is achanging magnetic field generated by an alternating current passingthrough the induction coil 512.

The powdered material in telemetry flux guide 518 may be held togetherusing any suitable material, such as a polymer material. In someexamples, the powdered metallic material may include iron and/or otherferrite materials. Additionally, the telemetry flux guide 518 may besuitable for frequencies of telemetry signals generated and/or receivedby the induction coil 512, such as, for example, an approximately 49 MHztelemetry signal and/or an approximately 10.7 MHz telemetry signal. Atelemetry flux guide 518 including a material having a relativepermeability (i.e., the ratio of the permeability of the alloy to thepermeability of free-space) of approximately 9 may be suitable for afrequency range that includes 49 MHz and 10.7 MHz telemetry signals.However, it will be recognized that the telemetry flux guide 518 mayhave any other suitable relative permeability value as may serve aparticular application. Additionally or alternatively, telemetry fluxguide 518 may have a relatively high resistivity and a relatively smallparticle size in order to facilitate redirection of magnetic flux whileminimizing the generation of eddy currents in the telemetry flux guide518.

The telemetry flux guide 518 may be positioned and configured to directmagnetic flux of the magnetic field generated by the induction coil 512away from the circuit board 506, as will be described in greater detailbelow. For example, a telemetry magnetic field may generated by theinduction coil 512 to transmit a telemetry signal. Magnetic flux of thetelemetry magnetic field may be directed away from the circuit board 506by the telemetry flux guide 518, thereby protecting the electroniccircuitry 508 on the circuit board 506 from the telemetry magneticfield. By directing the magnetic flux in the telemetry magnetic fieldaway from the circuit board 506, energy losses from the induction coil512 to the electronic circuitry 508 via the telemetry magnetic field maybe minimized, thereby extending the life of batteries used to providepower to one or more components of the cochlear implant system 100.

In some examples, the external headpiece 400 may additionally oralternatively include a retention magnet 522 disposed between thecircuit board 506 and the headpiece base 504. The retention magnet 522may have a top surface 524 generally facing the bottom surface 510 ofthe circuit board 506. The retention magnet 522 may additionally have anouter radial surface 526. In some embodiments, the retention magnet 522may be positioned in the external headpiece 400 such that the retentionmagnet 522 is at least partially surrounded by the induction coil 512and/or the telemetry flux guide 518. Accordingly, the outer radialsurface 526 of the retention magnet 522 may generally face the innerradial surface 516 of the induction coil 512 and/or the inner radialsurface 520 of the telemetry flux guide 518. For example, the retentionmagnet 522 may be positioned in an aperture defined by the inner radialsurface 520 extending through the telemetry flux guide 518.

The retention magnet 522 may be configured to produce a retentionmagnetic field for securing one or more components of a cochlear implantsystem 100 to a head 402 of a patient. For example, the retention magnet522 may be disposed adjacent to the headpiece base 504 such that theretention magnet 522 is in close proximity to the head 402 of thepatient when the headpiece base 504 is adjacent to the head 402. Aportion of the cochlear stimulation portion 104 of the cochlear implantsystem 100, such as the receiver 408 shown in FIG. 4, may similarlyinclude a magnet configured to magnetically couple with the retentionmagnet 522. Accordingly, when the headpiece base 504 is positionedadjacent to the head 402 of the patient near the receiver 408, theretention magnet 522 may be magnetically coupled to the magnet of thecochlear stimulation portion 104, thereby securing and/or orienting theexternal headpiece 400 on the head 402.

The external headpiece 400 may additionally or alternatively include aretention flux guide 528 positioned between the circuit board 506 andthe retention magnet 522. The retention flux guide 528 may at leastpartially surround the retention magnet 522. As illustrated in FIGS. 5Aand 5C, a top wall 530 of the retention flux guide 528 may be disposedin between and adjacent to the bottom surface 510 of the circuit board506 and the top surface 524 of the retention magnet 522. Additionally, aside wall 532 of the retention flux guide 528 may at least partiallysurround the outer radial surface 526 of the retention magnet 522. Theside wall 532 of the retention flux guide 528 may be adjacent to theouter radial surface 526 of the retention magnet 522, the inner radialsurface 516 of the induction coil 512, and/or the inner radial surface520 of the telemetry flux guide 518.

The retention flux guide 528 may include any material suitable forredirecting magnetic flux associated with a magnetic field produced bythe retention magnet 522. For example, the retention flux guide 528 mayinclude a material having a relatively high permeability. In someexamples, the retention flux guide 528 may include a metallic material,such as a mu-metal alloy comprising nickel and iron. A relatively highpermeability mu-metal alloy may have a relative permeability betweenapproximately 60,000 and 300,000. For example, a mu-metal alloy may havea relative permeability of approximately 100,000. A high-permeabilitymu-metal alloy may include any suitable ratio of nickel and iron, suchas, for example, a ratio of approximately 80% nickel and 20% iron. Itwill be recognized that the retention flux guide 528 may alternativelyinclude any suitable material having any suitable relative permeability.

The retention flux guide 528 may be configured to direct magnetic fluxof a retention magnetic field surrounding the retention magnet 522 awayfrom the circuit board 506 and/or away from the telemetry flux guide518. Accordingly, magnetic flux from the retention magnet 522 may bedirected away from the circuit board 506, thereby protecting theelectronic circuitry 508 on the circuit board 506 from the retentionmagnetic field.

As mentioned, the retention flux guide 528 may also direct magnetic fluxof the retention magnetic field away from the telemetry flux guide 518,thereby preventing saturation of powdered metallic material in thetelemetry flux guide 518 with magnetic flux from the retention magnet.Magnetic flux from the retention magnet 522 may significantly reduce therelative permeability of the powdered metallic material in the telemetryflux guide 518, reducing the effectiveness of the telemetry flux guide518 in directing magnetic flux from the induction coil 512 away from thecircuit board 506. Accordingly, the retention flux guide 528 may directmagnetic flux of the retention magnetic field away from the telemetryflux guide 518, thereby preventing magnetic flux from saturating thetelemetry flux guide 518.

By directing magnetic flux away from the electronic circuitry 508 in thecircuit board 506, the telemetry flux guide 518 and/or the retentionflux guide 528 may enable the induction coil 512 and/or the retentionmagnet 522 to be located within the external headpiece 400 in relativelyclose proximity to the circuit board 506. Accordingly, the soundprocessor portion 102 of the cochlear implant system 100 may be mademore compact by consolidating electronic and magnetic field emittingcomponents within the headpiece as illustrated in FIGS. 5A-5C. This mayincrease the ease of use and comfort for a patient using the cochlearimplant system 100 in comparison to conventional cochlear implantsystems in which electronic circuitry is separated from the headpiece.For example, a consolidated assembly, such as that illustrated in FIGS.5A-5C, may eliminate the need for a separate behind-the-ear assembly.Hence, the assembly illustrated in FIGS. 5A-5C may be referred to as a“one piece system headpiece”.

In some embodiments, the cochlear stimulation portion 104 of a cochlearimplant system 100 may additionally or alternatively include a retentionflux guide and/or a telemetry flux guide for directing magnetic fluxaway from electronic components in the cochlear stimulation portion 104.For example, a receiver 408 in the cochlear stimulation portion 104 mayinclude an induction coil and/or a retention magnet, similar to theexternal headpiece 400 as described above. A retention flux guide and/ora telemetry flux guide may be included in the receiver 408 to redirectmagnetic flux away from electronic circuitry that may be located inclose proximity to the induction coil and/or the retention magnet.

Additionally, as illustrated in FIGS. 5B and 5C, the external headpiece400 may include one or more batteries 534 to power the sound processorportion 102 and/or the cochlear stimulation portion 102 of the cochlearimplant system 100. Batteries 534 may be disposed within the headpiececover cavity 502 of the headpiece cover 500 and may be located adjacentcircuit board 506. In some embodiments, batteries 534 may be locatedoutside of the external headpiece 400.

FIG. 6 illustrates magnetic flux surrounding an induction coil 512 and aretention magnet 522 in an exemplary external headpiece 400 inaccordance with the present systems and methods. As illustrated in FIG.6, magnetic flux 600 may surround the induction coil 512. The magneticflux 600 is represented as a flux path surrounding the induction coil512. Additionally, magnetic flux 602 may pass through and surroundretention magnet 522. The magnetic flux 602 is represented as flux pathssurrounding and passing through the retention magnet 522. It will berecognized that additional flux paths other than those illustrated inFIG. 6 may be associated with the telemetry magnetic field surroundingthe induction coil 512 and the retention magnetic field surrounding theretention magnet 522.

The telemetry flux guide 518 may provide a low reluctance path for themagnetic flux 600 surrounding the induction coil 512. As illustrated inFIG. 6, the path of the magnetic flux 600 may be directed through thetelemetry flux guide 518 such that a path of the magnetic flux 600between the induction coil 512 and the circuit board 506 may beshortened. The magnetic flux 600 of the telemetry magnetic flux fieldsurrounding the induction coil 512 may therefore be redirected by thetelemetry flux guide 518 such that the magnetic flux 600 issubstantially prevented from reaching the circuit board 506, therebyreducing or eliminating magnetic flux passing through the electroniccircuitry 508.

The retention flux guide 528 may provide a high permeability path forthe magnetic flux 602 surrounding and passing through the retentionmagnet 522. As illustrated in FIG. 6, the path of the magnetic flux 602may be directed through the retention flux guide 528 such that a path ofthe magnetic flux 602 passes generally through and/or along the top wall530 and/or the side wall 532 of the retention flux guide 528.Accordingly, a path of the magnetic flux 602 between the induction coil512 and the circuit board 506 may be shortened. Similarly, a path of themagnetic flux 602 between the retention magnet 522 and the telemetryflux guide 518 may be shortened. The magnetic flux 602 of the retentionmagnetic flux field surrounding and passing through the retention magnet522 may therefore be redirected by the retention flux guide 528 suchthat the magnetic flux 602 is substantially prevented from reaching thecircuit board 506 and/or the telemetry flux guide 518, thereby reducingor eliminating magnetic flux from the retention magnet passing throughthe electronic circuitry 508 and/or the telemetry flux guide 518.

The preceding description has been presented only to illustrate anddescribe embodiments of the invention. It is not intended to beexhaustive or to limit the invention to any precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching.

What is claimed is:
 1. A cochlear implant system comprising: a componentthat houses a circuit board comprising electronic circuitry thatgenerates one or more signals; an induction coil that transmits the oneor more signals by generating a telemetry magnetic field; and atelemetry flux guide positioned between and in direct contact with a topsurface of the induction coil and a bottom surface of the circuit board.2. The cochlear implant system of claim 1, wherein the component furthercomprises a retention magnet that produces a retention magnetic fieldfor securing one or more components of the cochlear implant system to ahead of a patient.
 3. The cochlear implant system of claim 2, whereinthe retention magnet is positioned in an aperture extending through thetelemetry flux guide.
 4. The cochlear implant system of claim 2, whereinthe component further comprises a retention flux guide positionedbetween the retention magnet and the circuit board, wherein theretention flux guide directs magnetic flux of the retention magneticfield away from the circuit board.
 5. The cochlear implant system ofclaim 4, wherein at least a portion of the retention flux guide ispositioned between the retention magnet and the telemetry flux guide. 6.The cochlear implant system of claim 4, wherein the retention flux guidecomprises a metal having a comparatively high relative permeability. 7.The cochlear implant system of claim 1, wherein the telemetry flux guidehas an annular shape.
 8. The cochlear implant system of claim 1, whereinthe telemetry flux guide comprises a material having a relatively highresistivity that provides a low reluctance path for a magnetic flux ofthe telemetry magnetic field.
 9. The cochlear implant system of claim 1,wherein the telemetry flux guide comprises a powdered metallic material.10. The cochlear implant system of claim 9, wherein the powderedmetallic material comprises a ferrite material.
 11. The cochlear implantsystem of claim 1, wherein the component comprises an external headpiececonfigured to be secured to an exterior of a head of a patient.
 12. Thecochlear implant system of claim 1, wherein the one or more signalsinclude one or more stimulation parameters configured to direct animplantable cochlear stimulator to apply electrical stimulation to oneor more stimulation sites within a patient.
 13. The cochlear implantsystem of claim 1, wherein the telemetry flux guide directs magneticflux of the telemetry magnetic field away from the circuit board. 14.The cochlear implant system of claim 1, wherein the telemetry flux guideminimizes energy losses from the induction coil to the electroniccircuitry via the telemetry magnetic field.
 15. A cochlear implantsystem comprising: a component that houses a circuit board comprisingelectronic circuitry that generates one or more signals; an inductioncoil that transmits the one or more signals by generating a telemetrymagnetic field; a telemetry flux guide positioned between and in directcontact with a top surface of the induction coil and a bottom surface ofthe circuit board; a retention magnet that produces a retention magneticfield for securing one or more components of the cochlear implant systemto a head of a patient; and a retention flux guide positioned betweenthe retention magnet and the circuit board.
 16. The cochlear implantsystem of claim 15, wherein the retention flux guide directs magneticflux of the retention magnetic field away from the circuit board, andwherein the retention magnet and the retention flux guide are positionedwithin an aperture extending through the telemetry flux guide.
 17. Acochlear implant system comprising: an external headpiece configured tobe secured to an exterior of a head of a patient and comprising: acircuit board comprising electronic circuitry that generates a telemetrysignal, a first induction coil that transmits the telemetry signal bygenerating a telemetry magnetic field, and a telemetry flux guidepositioned between and in direct contact with a top surface of theinduction coil and a bottom surface of the circuit board; and animplantable cochlear stimulator implanted within the patient and thatincludes a second induction coil that receives telemetry signal.
 18. Thecochlear implant system of claim 17, wherein the telemetry flux guidedirects magnetic flux of the telemetry magnetic field away from thecircuit board.
 19. The cochlear implant system of claim 17, furthercomprising: a lead electrically connected to the implantable cochlearstimulator and comprising a plurality of electrodes in communicationwith one or more stimulation sites within a cochlea of the patient;wherein the telemetry signal directs the implantable cochlear stimulatorto generate and apply electrical stimulation to the one or morestimulation sites via the plurality of electrodes.
 20. The cochlearimplant system of claim 17, wherein the external headpiece furthercomprises: a retention magnet that produces a retention magnetic fieldfor securing one or more components of the cochlear implant system tothe head of the patient; and a retention flux guide positioned betweenthe retention magnet and the circuit board; wherein the retention fluxguide directs magnetic flux of the retention magnetic field away fromthe circuit board.